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SUMMARY:Flash talk: Beyond ΛCDM: Probing Structure Growth and Observation
 al Viability of Generalized f (Q\, Lm) Gravity
DTSTART;VALUE=DATE-TIME:20261119T080800Z
DTEND;VALUE=DATE-TIME:20261119T081000Z
DTSTAMP;VALUE=DATE-TIME:20261026T180018Z
UID:indico-contribution-959@indico.narit.or.th
DESCRIPTION:Speakers: RAJ  KUMAR DAS (Physics And Applied Mathematics Unit
  \,Indian Statistical Instiute Kolkata)\n$f(Q\, \\mathcal{L}_m)$ gravity i
 s a well-known extension of $f(Q)$ gravity\, obtained through non-minimal 
 or additive minimal coupling in the action's Lagrangian density. Existing 
 literature within the framework of $f(Q\, \\mathcal{L}_m)$ has explored th
 e cosmographic scenario through various approaches\, including background-
 level analyses and comparisons with $\\Lambda$CDM (Myrzakulov et al.\, Phy
 s.\\ Lett.\\ B 139506\, 2025\; Hazarika et al.\, Physics of the Dark Unive
 rse 50\, 102092\, 2025). In this work\, we investigate the additive minima
 l coupling in a generalized power-law form\, $f(Q\,\\mathcal{L}_m) = -Q^\\
 mu + \\alpha \\mathcal{L}_m^{\\\,\\nu} + \\beta$\, where $\\mu$\, $\\nu$\,
  $\\alpha$\, and $\\beta$ are the extra degrees of freedom introduced by t
 he model. We derive the key cosmological evolution equation\, the Hubble f
 unction $H(z)$\, by adopting a suitable novel parametrization. A distincti
 ve feature of this theoretical framework is the non-conservation of the ma
 tter sector (a non-conserved continuity equation)\, which we highlight and
  study under the condition $\\nu \\neq 1$\; this non-conservation is signi
 ficant\, as it effectively mimics a particle creation scenario. We constra
 in the model's free and extra parameters\, and examine their effects on th
 e cosmographic scenario\, using Observational Hubble Data (OHD)\, Baryon A
 coustic Oscillation (BAO) measurements from DESI DR2\, and three Type Ia S
 upernovae (SNe Ia) catalogs (Pantheon+\, Union3\, and the Dark Energy Surv
 ey). Since our framework inherently involves non-conservation\, we extend 
 the analysis beyond the background level to the perturbative regime\, deri
 ving the perturbed field equations of $f(Q\,\\mathcal{L}_m)$ together with
  the perturbed Euler and continuity equations\, and study the growth of st
 ructure and the impact of the non-conservation term on the growth equation
 \, further performing a joint observational analysis incorporating the $f\
 \sigma_8$ probe. To statistically assess our results\, we performed a Baye
 sian evidence analysis\, treating $\\Lambda$CDM as the reference model\; b
 ased on this analysis\, our non-conservative model shows a statistical edg
 e over $\\Lambda$CDM in several cases\, depending on the dataset combinati
 on used. These results position non-conservative $f(Q\,\\mathcal{L}_m)$ gr
 avity as a physically motivated and observationally testable alternative t
 o $\\Lambda$CDM\, rooted in an effective particle-creation mechanism.\n\nh
 ttps://indico.narit.or.th/event/234/contributions/959/
LOCATION:Pattaya\, Thailand D Varee Jomtien Beach Pattaya Hotel
URL:https://indico.narit.or.th/event/234/contributions/959/
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